The invention provides a protective device (10) for a needle assembly (12) having a needle hub (14) and a needle (16) projecting from the hub. The protective device includes an end cap (20) which has an opening (36) through which the needle (16) may pass, and a resilient member (22) extending about the needle (16) between the needle hub (14) and the end cap (20). The resilient member (22) is deformable between a first condition in which it holds the end cap (20) over a sharpened end (18) of the needle (16) and a second condition in which the end cap (20) is withdrawn from the sharpened end of the needle (16). Furthermore, the resilient member (22) is biased towards the first condition and is arranged to bias the end cap (20) into a safety position in which the sharpened end of the needle (16) is offset relative to the opening (36) in the end cap (20). The protective device (10) also includes a sheath (24) covering at least the sharpened end (18) of the needle (16). The sheath (24) extends into the opening (36) in the end cap (20) so as to hold the sharpened end of the needle (16) in alignment with the opening (36), against the bias of the end cap (20). The sheath (24) is also removable from the needle (16) to expose the sharpened end (18) for use, and after use, to allow the resilient member (22), upon return to the first condition, to automatically displace the end cap (20) into the safety position.